Backpack



FIG. 1 is a perspective view of the backpack showing the new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a right elevation view thereof;

FIG. 5 is a left elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The structural features depicted by broken lines in the drawing views have been shown for the purpose of illustrating portions of the backpack that form no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 